One problem with the use of highly portable communications devices such as personal communication devices and cellular phone type devices is providing security measures to assure privacy in communication. Encryption techniques are used to provide for secure, private wireless communication. Different levels of security are used depending on the type of information being communicated. Each level of security may use many different encryption/decryption algorithms. Typically there are four levels of security in communications used in the United States. These different levels generally apply throughout the world. Generally speaking, the encryption algorithms are segmented into the various levels because of the nature of the community that is being protected. For example, "level 1" security algorithms are for U.S. Government classified communications. "Level 2" and "level 3" security algorithms are used in a broader domain and are used in certain applications but it is desirable that these not be ubiquitous around the world. Level 4 algorithms are a weaker level of algorithms that provide general purpose privacy but are useable around the world. There is a need to be able to manufacture and distribute communications products that provide the different levels of security. The problem is how to provide and segment the products in accordance with the different levels of security.
Various measures have been proposed in the past to provide security in numerous applications in which it is necessary or desirable to limit access to a system. Passwords, for example, have been widely used to guard authorized access to computers and data. However, password verification schemes are most reliable when the password is manually entered and are not as effective when human interaction cannot be guaranteed. In other arrangements, electronic keys or tokens are used. Possession of the key or token identifies a user as being a valid user. The lack of possession of such a key or token would indicate that the user is not who he claims to be and he is denied use of the device. However, this arrangement is subject to unauthorized access occurring if an unauthorized user gains possession of the key or token.
Various arrangements have been proposed or utilized in the past in which a biometric of a person is used to verify or authenticate identification of a system user. "Biometric" as defined, for example, in U.S. Pat. No. 5,469,506, means a substantially stable physical characteristic of a person which can be automatically measured and characterized for comparison. In addition, biometrics may also include behavioral characteristics, such as the manner in which an individual writes his or her signature.
Increasingly, so called "smart cards" are used for a variety of purposes. A "smart card" is typically a credit card sized card that has a built-in microcontroller which enables the card to provide, modify or even create data in response to external stimuli. In many instances, the microcontroller is a single wafer integrated circuit which is mounted on an otherwise plastic credit card. Various smart card protection schemes have been devised to protect the unauthorized access to the data contents on such smart cards.
Split key systems help ensure key secrecy. In split key systems, an encryption key variable is used to encrypt the data. The key is then split, reduced, or otherwise manipulated into independent portions called splits and the original key is then destroyed. The action of splitting a key is referred to as reducing herein to avoid confusion with the end result of reduction (i.e., splits). A key may be reduced through any of a variety of mathematical operations which render the resulting splits virtually useless apart from one another but which allow the splits to be combined to recreate the original key.
In a split key system, one split or portion of the original key is stored in host equipment and the other split is stored elsewhere, such as in a removable and portable device. The portable device and host equipment need to be brought together to decrypt the data because neither the host nor the portable device has the complete key information necessary to decrypt the data on its own. When the portable device and the host equipment are combined, the original key can be regenerated from the splits (the portions of the original key), the stored information may be decrypted, and operations that use the encrypted data may be performed.
Some types of host equipment grant access to multiple portable devices. This is accomplished by having the host equipment contain a number of different splits of the key. Any portable device having an appropriate split to match one of the host splits can then be used to access the encrypted data. Likewise, some portable devices store multiple splits, allowing them to be used to access separate databases stored on different host equipment.
One problem in the past with providing secure functions in portable host devices such as a cellular telephone or personal communications device, is that each host typically may be utilized only for a single level of security. To provide for different levels of secure functions, different portable hosts are utilized, each requiring a different secure access token.
An additional problem is to provide access control, anti-tamper functionality and variable security levels in devices such as wireless telecommunications devices. It would be desirable to provide a wireless communication device that is universally useable over a range of secure functions.